49ers free agent acquisition Earl Mitchell has been unblock-able at times in training camp.

49ers free agent acquisition Earl Mitchell has been unblock-able at times in training camp.

Photo: Special to The Chronicle

Image 12 of 13

Fifth-round pick Marquel Lee might end up as the Raiders starting middle linebacker.

Fifth-round pick Marquel Lee might end up as the Raiders starting middle linebacker.

Photo: The Chronicle

Image 13 of 13

The 49ers' defense will be better than the Raiders' and here's why

1 / 13

Back to Gallery

The Raiders, with their prodigious offense, newly minted quarterback, star-studded offensive line and talented receiving corps seem set for another playoff run. The struggling 49ers once again look like a talent-challenged group where the playoffs will be a mirage for possibly years to come.
However, one area where the teams might going in reverse is with their defenses. The Raiders had one of the worst units in the league last year and so did the 49ers. But San Francisco has now been outfitted with a new scheme, a raft of new players, and the physical mentality.

In Napa, the Raiders look like they will trot out a similar group of players and then wish for different results. Here’s why the 49ers will have a better defense than the Raiders this year:

-The Raiders ranked 26th in the defense the last two years, and other than the draft, they didn’t do much to upgrade their personnel.

-The Raiders are likely to send a very similar secondary to the one that gave up a league-leading 61 receptions of over 20 yards or more. They also led the league in yielding the most 40-yard receptions.

-The Raiders have a tremendous pass rusher in Khalil Mack and Bruce Irvin also contributes. They combined for 18 total sacks last year, but the rest of the team chipped in just seven as the Raiders combined for a league-low 25 sacks last year.

-The Raiders might have too many cooks in the kitchen in terms of coaching. Former 49ers linebacker Ken Norton Jr. is still the defensive coordinator, however the team has hired former Chargers defensive coordinator John Pagano as an assistant head coach and de facto coordinator.

-The team is frightfully thin at linebacker and might even start a fifth-round rookie, Marquel Lee, at middle linebacker.

-Unrestricted free agent cornerback Sean Smith struggled last year at cornerback, and the team might not have anyone else to replace him.

-Although the 49ers haven’t set their starters, they are surprisingly deep largely due to their defensive-oriented drafts.

-Defenders have all gotten the message that defensive coordinator Robert Saleh wants faster, lighter players. In training camp, the defense appears much more active.

-The 49ers are taking to Saleh’s severely pared down scheme and his philosophy of getting up the field. At this stage, the defense is far ahead of the offense.

-The 49ers present an unusual challenge for any offense because of the length and height of their defensive line in particular. Defensive linemen Arik Armstead, DeForest Buckner and Aaron Lynch are all over 6-foot, 6-inches.

-The defense’s variety could provide unique problems for an offensive tackle. On one down they could face the 6-8 Armstead, and on the next down, encounter the 5-foot, 11-inch Elvis Dumervil.

-New defensive tackle Earl Mitchell has been unblock-able at times in practice and he also has become a leader of the defensive line group.

-Like the Raiders, the 49ers’ secondary is their biggest question, however, second-year player Rashard Robinson looks like he’s now a legitimate NFL starter.

-So far in camp, rookie linebacker Reuben Foster has been a star, particularly with his pass coverage, which is something he rarely did in college.